Question

From a metallic wall at 100$^\circ$C, a metallic rod protrudes to the ambient air. The temperature at the tip will be minimum when the rod is made of:

• A. Aluminium
• B. Steel
• C. Copper
• D. Silver

Hint:

Lower thermal conductivity leads to less heat reaching the rod's tip — making steel the best choice for lowest tip temperature.

Answer 1

The Correct Option is B

In this scenario, the rod acts as a fin dissipating heat from the wall to the surrounding air.
The temperature distribution along a fin depends on the material's thermal conductivity.
- Materials like copper, silver, and aluminium have high thermal conductivity, allowing efficient heat transfer from the wall to the tip — resulting in a higher temperature at the tip. 
- Steel has relatively low thermal conductivity compared to the others, resulting in poorer heat conduction and thus a lower temperature at the tip.
Hence, the rod made of steel will have the lowest tip temperature among the options.